Tape made by group in class (8)
I believe the answer is:
cassette
'tape' is the definition.
(I know that tape can be written as cassette)
'group in class' is the wordplay.
'group' becomes 'set' (both can mean a collection).
'in' indicates putting letters inside.
'class' becomes 'caste' (type of social class).
'set' inserted into 'caste' is 'CASSETTE'.
'made by' acts as a link.
(Other definitions for cassette that I've seen before include "something from old-fashioned language laboratory?" , "Music tape" , "One records" , "Tape unit" , "sealed plastic container" .)